Circuit interrupting device



Oct. 28, 1947. E, A, wlLLlAMs', JR" ETAL I AS CIRCUIT INTERRUPTING DEVISE' Filed June 29, 1944 f Edwin AWM Hams-Jr.; Arrifc HPOw-el l Their Attnrrwey,

Patented-Oct. 19.47

Sv PATENT OFFICE-l anarco cracurr manaur'rmc. DEVICE Edwin A. Williams, Jr., Lansdowne, and Alrlc l-l. Powell, Yeailon,4 Pa... signora 1 to General .Electric Company, a corporation ot New Yori;

Application June v2li, 1944, Serial No. 542,726

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Our invention relates to circuit interrupting devices, and more particularly to circuit interrupting devices oi the type employing fusible elements.

Although the circuit interrupting devices of our invention to be described hereinafter may have many applications, they are particularly adapted for use on air craft. At the present time the motors and controls on large air craft have generally been supplied from a direct current source oi power. It has recently been proposed to supply the electrical energy for the various motors and controls on large air craft with alternating current oi' a frequency in the neighborhood of 400 cycles. 'I'he circuits for supplying this power are arranged so as to comprise numerous parallel paths each taking a more or less diderent .(Cl. 20G- 113) course, and each ofk these parallel paths must be protected by suitable circuit interrupting devices. The circuit interrupting device of our invention to be described hereinafter, has been found very satisfactory for such use. The arrangement described 1above provides selectivity and allows proper fimctioning oi' the various electrical loads on the air craft even though one or more of the connecting circuits may become damaged for some reason or other.

It is an object of our invention to provide a new and improved circuit interrupting device of the type employing one or more fusible elements. It is another object of our invention to provide a new andl improved fuse device having an operating characteristic which is independent of the altitude at which it operates, which has a uniform arcing time, and which is inexpensive to manufacture and accurate and dependable in operation. v

It is another obiect of our invention to provide a new and improved fuse device of the sand iilled type comprising a unitary construction for protecting a plurality of independent circuits or a plurality of phases of the same circuit.

Further objects and advantages of our invention will become apparent as the following description proceeds and the features of novelty which characterize our invention will be pointed 2 ly sectional view taken on line 3-3 of Fig. 2, and Fig. 4 is a left-hand end view of Fig. 2.

Referring now to the drawings, the fuse device of our invention comprises a, plurality of short conductors I, the number depending upon the number of independent fused paths in the fuse device of our invention, since two are employed for each independent fused path. These conductors have been illustrated as short bladelike members, three of them lbeing shown for each end of the fuse device since a three-phase fuse or a fuse having three independent current paths therethrough is illustrated. The three blade-like conductors I atthe right-hand side of Fig. 2 of the drawing are molded in spaced parallel relationship into an insulating fuse ierrule, or member, 2, while the three left-hand members are molded in spaced parallel relationship into an insulated member or ferrule 3. The insulating members or ferrules 2 and 3 are substantially identical except for the fact that insulating member 3 is provided with a plurality of openings 4, one adjacent each blade-like conductor I, the purpose of which will become apparent as the following description proceeds. Each of the insulating members or ferrulesV 2 and 3 is provided with a plurality of circular recesses 5 disposed on the opposite side of the ferrules from which conductors' I extend and arranged s o that the conductors I extend to the bottom of the`recess and are centrally disposed with respect to the recess.

The recesses are adapted to accommodate the ends of fuse tubes preferably formed of transparent insulating material, such as glass, generally indicated at t in .the drawing. The insulating ferrules 2 and 3 are each placed on opposite ends of a plurality of fuse tubes IiV with the ends ofthe fuse tubes fitted into the appropriate recesses 5. In order to seal the ferrules 2 and 3 to the fuse tubes', a suitable cement l is provided on the end of each tube 6 to be inserted into the corresponding recess 5. The fuse device is held as a unitary assembly by means of suitablefastening means, such as the screws indicated at 8 in the drawings whereby the ferrules 2 and 3 are firmly clamped together and by virtue of the cement l into sealing engagement with the fuse tubes 6.

One or more openings, such as 9 and l0, are drilled longitudinally through each of the bladelike conductors I to accommodate one or more fusiblel elements. In the drawings each fuse tube is illustrated as being provided with two fusible elements such as II and I2, which fusible elements are threaded through-th corresponding deposited on the tube surface.

openings 8 and Il, respectively. To simplify the drilling operation for holes or openings l. each of the blade-like conductors I may be provided with a notched portion Ii (Figs. 3 and 4). The

ends of the fusible elements II and I2 are suitably soldered to blade-like conductors I, as indicated at I4. 1f only a single fusible element is employed in each, fuse tube l, this fusible element would comprise the conductor II and the fusible element 'I2 would not be provided.

In order that the fuse device of our invention may have a characteristic independent of altitude 'together with a uniform arcing time, the

tubular casing 8 are filled with an inert, gran ular, arc extinguishing material such as sand or fused quartz indicated'at I5 in the drawings.

This inert arc extinguishing material is put into the tubes 8 through openings l which are subsequently sealed with a filler plug I5 preferably formed of a suitable cement similar to the cement 1 mentioned above. This filler of granular material I5 provides the fuse device of our invention with desirable current limiting action at high currents. In addition the sand provides vibration damping thereby preventing breakage of the fusible elements I I and I '2 through fatigue of the metal by stress reversal.

In order to indicate operation of the fuse device of our invention, at least the fusible elements II are mounted very near to the surface of the glass tube 8 whereupon the condition of the wire will be visible; Rupture of the fusible element when it is close to the glass tube even though it does not actually touch the tube, as indicated in the drawings, will still indicate operation of the fuse device by virtue of the metal If desired, the interior surface of the fuse tube B may be coated with a thin film of changeable color coating'material, which material will change its color upon rupture of the fusible element II. Such an indicating means is disclosed and claimed in copending Skeats application, Serial No. 539,535, flied June 29, 1944, and assigned to the same assignee as the present application.

. In Fig. 1 we have illustrated the multi-circuit fuse device of our invention as mounted inv a suitable base provided with a plurality of terminals Il, having spring 'clips Il for engaging the blade-like conductors I. The construction of the base shown in Fig. 1 is not our invention, but is disclosed end claimed in the copending application of Alric H. PowelLB. N. 542,725, filed concurrently with this application and assigned to the same assignee as the present application.

The fuse device of our invention is constructed by first molding the ferrules 2 and 3 from suitable insulating material with the blade-like conductors I molded therein in spaced parallel relationship. The recessesl 5 are also molded therein. A plurality of glass tubes B are then carefully selected so as to have substantially the same length. The blade-like conductors 'I are drilled with theopenings 9 and I'Il and the tubes B and ferrules 2 and I are then assembled by stringing the fusible wires II and I2, if two wires are used. through the openings in the bladelike conductors associated with one of the ferrules, such as 2 for example, then through the glass tubes and then through the respective.

openings 9 and III in the blade-like conductors I associated with the other ferrule, such as i. Cement 'I is then placed on each end of the glass tubes and the parts are pushed together and held in this manner by the screws I. The wires Il that we have provided a small, compact, ugra- Il .bers so as to extend outwardly from said mem-I weight fuse device which is relatively simple and inexpensive to manufacture and yet provides satisfactory interrupting operation under all conditions. Whenever one of the fusible elements ruptures the entire unit is replaced and consequently there is no danger of leaving in the circuit a fusible element which may have been damaged but which is not actually ruptured.

Although we have elected to describe and illustrate herein a preferred embodiment of our invention as employed in a fuse device` as well as the process of construction thereof, it is contemplated'that other applications of our invention to fuses or like electrical devices other than the particular form illustrated will suggest themselves to those skilled in the art. It is intended that such other applications or modifications as do not depart from the true spirit and scope of our invention will be covered by the appended claims. l

What we claim as new and desire to secure by Letters Patent of the United States is:

1. In an electric fuse device a pair of members formed of molded insulating material, a plurality of blade-like conductors for each of said members forming the terminals of said fuse device, a plurality of said blade-like conductors being molded in spaced parallel relationship in each of said members so as to extend outwardly from said members, a plurality of tubes of insulating, material directly engaging and interconnecting said members and a fusible element in each of said tubes interconnecting one blade-like conductor on one member with the corresponding blade-like conductor on the other member.

2. In an electric fuse device a pair of members formed of molded insulating material each of said members being provided with a recess, a pair of conductors one for each of said members forming the terminals of said fuse device, one of said conductors being molded in each of said members so as to extend outwardly through the members from the bottom of the recesses therein, a tube of insulating material having its ends seated in said recesses and a fusible element in said tube interconnecting the conductors on said members.

3. In an electric fuse device a pair of ferrules formed of molded insulating material, a pair of blade-like conductors one for each of said ferrules. one of said blade-like conductors being molded in each of said ferrules so as to extend outwardly from said ferrules, a tube oi' insulating 'material independent of said ferrules directly engaging -and extending between said ferrules and a fusible element in said tube interconnecting the blade-like conductors on said ferrules.

4. In an electric fuse device a pair o f members formed of insulating material, a plurality of blade-like conductors for each of said members forming the terminals of said fuse device, a plurality of said blade-like conductors being held in spaced parallel relationship in each of said members, a plurality of tubes of insulating material directly engaging and interconnecting said members, a fusible element in each of said tubes interconnecting one blade-like conductor on one member with the corresponding blade-like conductor on the other member, and means for holding said fuse device as a unitary structure.

4 ductor on the other member, and a. granular inert material filling each of said tubes and embedding said fusible elements.

6. In an electric fuse device a pair of members formed of molded insulating material each of said members being provided with a substantially cylindrical recess, a pair of conductors one for each of said members forming the terminals of said fuse device, oneof said conductors being molded in each of said lmembers so as to extend outwardly through the members from the bottomsoi' the respective recesses therein, a tube of insulating material having its ends seated in said recesses, a fusible element in said tube interconnecting the conductors on said members, and an inert granular insulating material within said tube embedding said fusible element.

7. In an electric fuse device a pair of members formed of molded insulating material, a pair of conductors one for each of said members forming the terminalsl of said fuse device, one of said conductors being molded in each of said members s o as to extend outwardly from said members, a tube of insulating material directly engaging and interconnecting said members, a fusible element in said tube interconnecting the conductors on said members, means defining an opening in one of said members leading into said tube, an inert granular arc quenching material filling said tube around said fusible element, and means for sealing said opening. 4

` EDWIN A. WILLIAMS, JR.

ALRIC H. POWELL.

' REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 871,851 Young I- Nov. 26, 1907 897,525 De Reamer Sept. 1, 1908' 1,212,603 Baker Jan. 16, 191'! 1.339,965 Murray May 11, 1920 2,337,937 Seriiing et al Dec. 28, 1943 FOREIGN PATENTS Number Country Date 15,646 Great Britain Nov. 20, 1911 

